I have used this on three different racks, including two Old Man Mountain *super* heavy duty bike racks which are hard to fit for most add ons like this (reflector kits, blinkie light holders, etc usually don't fit).
I initially bought the adapter because my youngest daughter sat on the bike rack on her way to and from school each day. Once I got the Travoy trailer, I wanted to be able to multitask and do my grocery shopping/errands after dropping her off. Without the adapter, this wasn't posssible as her butt would have been on top of the arm of the trailer. I was able to place the adapter far back on the rack, toward the rear, not on the front of the rack like in the stock photo. For two years, this was the solution and it worked terrifically well until she began riding her own bike. Later, I needed more storage capacity for my weekly grocery runs. Adding panniers to the Travoy's capacity does the trick for all but the most enormous shopping needs, but my awesome Arkel city shoppers that I have sit too high, interfering with the Travoy's clearance on turning. I tapped into the old adapter that I had, and voila, problem fixed. By moving the hitch to the back of the rack, I can use my Travoy AND my panniers!
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I've used this adapter on three different bikes with three different racks. All have fit well--although not symmetrically on one of my racks. My cheaper rack forced me to place the adapter slightly off center. I pushed it more to the "passenger" side of the bike as I almost always mount from the left hand side and didn't want to worry about hitting it with my leg by accident. Burley could improve this by drilling 3 sets of holes rather than the existing two, although maybe that would compromise the strength of the hitch? Not sure, but it would be handy to have that option for more precise adjustability.
Be aware that racks that have a bend can require

I have used this on three different racks, including two Old Man Mountain *super* heavy duty bike racks which are hard to fit for most add ons like this (reflector kits, blinkie light holders, etc usually don't fit). I initially bought the adapter because my youngest daughter sat on the bike rack on her way to and from school each day. Once I got the Travoy trailer, I wanted to be able to multitask and do my grocery shopping/errands after dropping her off. Without the adapter, this wasn't posssible as her butt would have been on top of the arm of the trailer. I was able to place the adapter far back on the rack, toward the rear, not on the front of the rack like in the stock photo. For two years, this was the solution and it worked terrifically well until she began riding her own bike. Later, I needed more storage capacity for my weekly grocery runs. Adding panniers to the Travoy's capacity does the trick for all but the most enormous shopping needs, but my awesome Arkel city shoppers that I have sit too high, interfering with the Travoy's clearance on turning. I tapped into the old adapter that I had, and voila, problem fixed. By moving the hitch to the back of the rack, I can use my Travoy AND my panniers! I've used this adapter on three different bikes with three different racks. All have fit well--although not symmetrically on one of my racks. My cheaper rack forced me to place the adapter slightly off center. I pushed it more to the "passenger" side of the bike as I almost always mount from the left hand side and didn't want to worry about hitting it with my leg by accident. Burley could improve this by drilling 3 sets of holes rather than the existing two, although maybe that would compromise the strength of the hitch? Not sure, but it would be handy to have that option for more precise adjustability. Be aware that racks that have a bend can require